The Hoover Dam: Steel Wonders of the World

21 June 2016

Completed in 1935 – and taking just four years to build – the Hoover Dam is one of the biggest tourist attractions in the US, attracting an average of 7 million visitors each year. It’s also a Steel Wonder of the World and we’ll be focusing on this man-made marvel for our third blog post in our four-part series.

On this scale, concrete would not have worked without steel

Dam walls require an enormous amount of concrete. A total of 2, 480,000 cubic metres of concrete was used in the construction of the Hoover Dam wall alone, with another 850,000 cubic metres going into additional structures such as the power plant and other related works.

Engineers at the time calculated that if the dam was built in one continuous concrete pour, it would take 125 years to cool, so instead of a continuous pour method, concrete blocks in columns were poured.

Some of the columns were as large as 15m x 15m square and 1.5m high. Each column contained a series of steel pipes. The curing process for these concrete columns involved first running cool river water and then cold water from a refrigeration plant through the pipes to cure the concrete. When this process was finalised the steel pipes were filled with grout. This cooling method ended up using 965 kilometres of steel pipework.

Building a dam with big buckets

As well as using steel to cool and reinforce the concrete, the more eye-catching role that steel played in the construction phase of the project was in the form of the massive steel buckets that were used to deliver the concrete around the site. These steel buckets were 2.1m high and almost the same again in diameter.

The buckets weighed 20 tons once they were filled with concrete. Once the steel buckets were filled at the concrete pants in Nevada, they moved to site via railway and then suspended via steel cableway and transported through the air to a specific column. The 6.1 cubic metres of concrete was then poured into the form, covering the steel pipework. Using this method, a bucket of concrete was able to reach the column pouring team every 78 seconds.

It’s difficult to realise the scale of this Dam – which is why visitors from around the world flock there. Some vital statistics about this engineering marvel include:

When it was finished in 1935, the Hoover dam wall was the tallest in the world

The Hoover dam is capable of irrigating two million acres and powering 1.3 million homes

Construction of the dam involved a workforce of 21,000 people

Around 112 deaths have been associated with the construction of the dam, not including those that died of pneumonia

The amount of concrete used in the dam structures is enough to pave a two-lane highway from San Francisco to New York

Despite its amazing statistics, the Hoover Dam was only the largest hydro-electric power plant for 10 years, from 1938 to 1948. As a sign of just how far engineering, earthmoving and construction techniques have come, the Hoover power station is now only ranked at 59 in the list of the world’s largest power stations.